James Ryan of Leinster is tackled by Jacques Du Plessis, left, and Kelian Galletier of Montpellier during the European Rugby Champions Cup Pool 3 Round 1 match between Leinster and Montpellier at the RDS Arena in Dublin. Photo by Ramsey Cardy/Sportsfile

Leinster head coach Leo Cullen was relieved after his side began their European Champions Cup campaign with a hard-earned 24-17 bonus-point win over Montpellier.

Ruan Pienaar's 70th-minute penalty for the visitors set up a tense finale with just seven points between the sides, but despite losing Adam Byrne to the sin-bin for the final five minutes, Leinster hung on.

The 22-year-old fly-half Ross Byrne was one of a number of young players to step up, with lock James Ryan and winger Daly making their Champions Cup debuts, and Cullen expects them to benefit from the experience.

"James had done a lot of Scott's roles during the week," he added.

"I thought he was very strong in contact, James. He's a good athlete, good engine. It's tough trying to take down a lot of those big guys, but I thought he did well.

"Again, that's why Barry Daly got picked, because he's able to score tries. I thought he was really good the way he finished.

"It's a huge step up for those guys. Guys are coming in for their first games here in Europe, so they're only going to get better for that experience."

Meanwhile, Montpellier forwards coach Nathan Hines filled in for head coach Vern Cotter, who was unable to travel due to personal reasons.

A try in each half from their bulldozing Fijian winger Nemani Nadolo, coupled with Pienaar's seven-point haul, earned Montpellier a losing bonus point.

"Honestly, we didn't play the way we planned," said Hines.

"We're a bit disappointed with our structure of play and to be honest I think every time we tried to apply pressure, we turned over the ball, or a little bit of indiscipline cost us.

"We can't afford to make those kind of errors, especially against a team like Leinster who make you pay. We were forced into errors and some were unforced."